Recently, display devices that include a touch display panel for inputting a signal on a screen using a pen, a finger, and the like have been widely used without a separate input device such as a remote controller and a keypad. The touch display panel may be classified into a pressure sensitive (resistive film) type, a capacitive (capacitance) type, and a touch recognition type of which an imaging device uses an infrared (IR) illumination according to a method of detecting a touch.
In the pressure sensitive type touch display panel in the related art, a pressed spot is detected (e.g., a location of where pressure is applied) by a short-circuit between an upper electrode and a lower electrode by pressing the touch display panel using a finger and a pen as a touch means. Accordingly, an accurate touch input may be obtained. However, since a multi touch is not possible, when many points are touched simultaneously, an error in touch recognition may occur and a reaction speed may be slow.
In the capacitive type touch display panel in the related art, a change in any charge amount is detected to detect the touch spot by touching the touch display panel with a finger and an exclusive pen as a touch means. Accordingly, the touch speed may be improved, and screen clearness and transmittance may be greater than the resistive film type touch display panel. However, due to a physical surface movement of the screen, signal distortion may occur, and thus the accurate touch recognition may not be obtained. Further, since the charge amount of the touch spot needs to be changed, only a limited touch means may be available, and touch recognition by a nail, a glove, or the like may not be obtained.
In the touch recognition type touch display panel in which the imaging device uses the IR illumination in the related art, greater transmittance and greater accuracy may be obtained than the pressure sensitive type or the capacitive type. However, to secure an imaging device viewing angle, an empty space may be further required, and an error in the touch recognition may occur by light-disturbance, such as solar light.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.